What exactly makes some species more aggressive than others?

[Deadeye]

So I know that things like nasties or Cubans are the only fish in their area, so they are naturally dominant, but what about the species that live with others.
The big guys like parachromis or amphs are large piscivores, is that why they are so mean, or is there something else?
I guess what I’m asking is, what factors specifically contribute to why certain families or species are so much more aggressive than others?

 

[Cich Mind]

I'm pretty sure duanes would be able to help on this subject.

 

[Kolton13]

Genetics. If a naturally agressive fish breeds with a really personable fish. its a 50% chance that the fish will be nice or aggressive.

 

[dogofwar]

Remember that fish, even when you take them from nature and place them in a glass box, are behaving how they have evolved.

Many cichlids are territorial because their reproduction depends on guarding their eggs and young (vs. scattering eggs or other reproductive strategies).

Maybe it's on Youtube somewhere but Ad Konings put out a DVD on feeding strategies for cichlids of Lake Malawi. Mbuna with the ability to eat algae and other "food" from lots of places don't need to be territorial to survive. The ones that don't have that adaption need to maintain a territory - and defend it - where algae can grow long enough that they can eat it (or else they'll be out-competed by others).

Some fish are better suited to aquariums than others for these kinds of reasons.

 

[FJB]

A number of things would play roles on determining levels of aggression typical of various species.
Among them,
- Type of diet (food) and relative abundance of food. Predators would tend to consider anything that fits, as food.
- Reproductive biology. Do they maintain territories, and are territory elements limiting in the habitat.
- Habitat size, density of fish, and shelter availability (if needed)
- Presence of other, potentially more aggressive species in same habitat
- Relative levels or stability or frequency of disturbance evens that 'rearrange' habitat
- And others, including 'genetics'. However, the later is modulated by all of the aspects above.

 

[tlindsey]

A number of things would play roles on determining levels of aggression typical of various species.
Among them,
- Type of diet (food) and relative abundance of food. Predators would tend to consider anything that fits, as food.
- Reproductive biology. Do they maintain territories, and are territory elements limiting in the habitat.
- Habitat size, density of fish, and shelter availability (if needed)
- Presence of other, potentially more aggressive species in same habitat
- Relative levels or stability or frequency of disturbance evens that 'rearrange' habitat
- And others, including 'genetics'. However, the later is modulated by all of the aspects above.

Great point's by both D dogofwar and F FJB .

 

[Deadeye]

All environmental factors then, pretty much what I was thinking.
Essentially if we gave convicts a couple million years in place of a dovii, it would become like a dovii (assuming it can adapt properly to its new environment and role).

 

[Backfromthedead]

I think a specific cichlid types aggression most likely rises from interspecific competition throughout their evolutionary history. In natural environments cichlids have to defend their food and young from catfish and other large predators. Those cichlids who have evolved to be highly aggressive are those that are more solitary and predatory in nature, and outright compete with the larger predators in their range; whereas the more community oriented cichlids have been able to successfully evolve through strength in numbers and predator satiation.

 

[dogofwar]

Not exactly. It's about competition and adaption to a niche. Convicts and Parachromis serve very different roles in their respective (and shared) habitats. Remember that fish tanks and nature are two wildly different things.

Here's a good overview of the topic of cichlid evolution:

All environmental factors then, pretty much what I was thinking.
Essentially if we gave convicts a couple million years in place of a dovii, it would become like a dovii (assuming it can adapt properly to its new environment and role).

 

[duanes]

I don't consider Parachromis "mean".
They are simply predators, and each require a very large territory.
To me for large fish, its all about tank size, and to house them in a community situation a couple hundred gallons is not even close to meeting their actual needs.
If you watch any of Mels large cichlid youtube videos, most often his Parachromis and other large cichlids seem quite docile.
But most of his tanks are 300 gallon, and move up into the 500 and 1000 gallon range for large adults.

One other thing I've found is, certain riverine and rheophillic species like those of the genus Tomocicha, Theraps and Maskaheros come from very strong constant, heavily moving walls of water, so in nature they are constantly working against a moving wall.
Without the regular use of that energy they have evolved to deal with, it has to go somewhere, and often ends up turning into aggression if not used up.
If these rheophilic species are given the constant current, and a large enough tank, the aggression may be minimal.
Things like aerators, HOB filters, or canisters, do not come close to providing this type water movement.
Even for the small Andinoacara species (largest 7") I am keeping at the moment, I'm providing a 1500 GPH pump cycling thru the sump, and have added a another powerhead type pump to the tank, to push a linear wall current of water (as close as I can) to mimic the moving current of the river they were caught in